Interaction of insecticides with human plasma lipoproteins

The binding of chlorinated hydrocarbon, carbamate and organophosphate insecticides to human low density plasma lipoproteins (LDL) and high density plasma lipoproteins (HDL) was studied at pH 7.0 and 16°C and 26°C by equilibrium dialysis, difference spectra and fluorescence. The results suggest interaction to be a partitioning rather than a stoichiometric binding process. Distribution is related to lipid content and composition of the lipoproteins. The K-values vary from 3 × 10⁵ M^?1 for 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) to less than 10 M^?1 for nicotine and aldicarb, and ΔG_tr° is in the range of 7400 cal for DDT to less than 1000 cal for aldicarb and nicotine. The K and ΔG_tr° are inversely related to the water solubility of the insecticides. A significant role of plasma lipoproteins in the transport of slightly water soluble insecticides is suggested.